THE FACE. 1175 
anterior part of the middle turbinal is seen when the patient’s head is thrown well 
back ; between it and the septum is a slit-like interval (olfactory cleft). By rotat- 
ing the patient's head towards the corresponding shoulder the anterior part of the 
middle meatus is brought into view; pus in this situation may originate from the 
frontal, the anterior ethmoidal, or the maxillary sinuses, all of which open into the 
hiatus semilunaris of the middle meatus (Fig. 490). 
To make a satisfactory digital exploration of the anterior part of the nasal 
cavities, it is necessary to divide the columella and the cartilaginous septum with 
a strong pair of scissors, one blade being introduced into each nostril (Kocher); 
blood spurts from the small arteries of the septum, but the bleeding soon ceases. 
When these vessels, which are derived from the superior cor mary arteries, are the 
source of the hemorrhage in epistaxis, the bleeding can be arrested either by com- 
pressing the coronary arteries, by plugging the anterior nares, or by grasping the 
cartilaginous part of the nose firmly between the finger and thumb. 
The maxillary sinus or antrum of Highmore, situated in the upper jaw, is a 
pyramidal cavity with its base formed v the outer wall of the nose and its apex 
directed towards the malar bone (Fig. 121). The cavity is lined by a thin muco- 
periosteal membrane, easily separable from the bone; in the mucous layer are 
numerous mucous g lands from which cysts may dev elop. The floor of the antrum, 
which is normally on a level with the floor of the nose, is separated from the roots 
of the bicuspid and molar teeth by a plate of bone of varying thickness. When this 
plate is thin and devoid of spongiosa, the floor of the antrum sinks below the level 
of the floor of the nose, and suppuration at the roots of one of the teeth above 
mentioned is in these circumstances very Hable to extend to the antrum. In an 
antrum of average dimensions the line of union of the nasal and facial walls of 
the cavity corresponds externally to the outer edge of the canine ridge (Logan 
Turner). The antral orifice is situated at the highest part of the antrum, and 
is therefore unfavourably placed for natural drainage ; it opens into the posterior 
and lower part of the infundibulum which, in its turn, communicates with the 
middle meatus of the nose through the hiatus semilunaris, Tn old age there is 
frequently a second communication between the antrum and middle meatus, the 
opening being situated behind and below the normal orifice ; when this accessory 
osteum exists pus from the antrum may drain backwards into the naso- pharynx 
(Logan Turner). In empyema of the antrum the opening to evacuate and drain 
the cavity may be made (1) through the alveolus of the second bicuspid or of the 
first or second molar tooth, the first molar being the site of election ; (2) through 
the canine fossa, external to the prominence caused by the root of the canine tooth ; 
or (5) through the outer wall of the inferior meatus of the nose. 
Lips. i compressing the coronary arteries, it must be remembered that they 
run beneath the mucous surface of the lips a short distance from their free margins. 
The lips are abundantly supphed with mucous glands which can he felt immediately 
beneath the mucous membrane nearer their attached than their free borders ; the 
glands are a frequent source of mucous cysts; occasionally they are enlarged 
congenitally, giving rise to one form of hypertrophy of the lip. 
Hare-lip is due to failure of the union of the internal nasal subdivision of the fronto-nasal 
process with the maxillary process. The deformity is spoken of as complete or incomplete 
according as the cleft extends into the nostril or merely involves a portion of the 
lip. The fissure may involve the lip only, or it may include the alveolar process of the 
jaw ; in the latter case the cleft may or may not be associated with a cleft of the palate. 
Lastly, the hare-lip may be single or double, according as the deficiency has occurred on 
one (usually the left) or both sides; in the latter case the central portion of the lip and 
the premaxillee project more or less markedly from the nasal septum. 
Teeth.—The milk teeth begin to appear from the sixth to the eighth month, the 
first to emerge being the lower central incisors. The first dentition is completed 
about the thirtieth month. Delayed dentition is generally due to rickets. Of the 
permanent set the first to erupt are the first molars, which appear at the end of the 
sixth or seventh year; the third molars (wisdom teeth), the last to appear, may 
erupt any time between the eighteenth and the twenty-fifth year, or even later. 
Bi: 
